Such devices are especially used to make offset controls for various automobile seat adjustment mechanisms, for example, to control the position locking of the articulation mechanism of the backrest with respect to the seat pan by means of a control handle located on the side of the seat pan, offset towards the front of the seat in relation to the said articulation.
Such a known device is shown on FIG. 1, where an articulation mechanism 1 can be seen, installed between the framework of the seat pan 2 and the framework of the backrest 3 and including a link 4 enabling the mechanism to be unlocked in a manner known in the art. The pivoting of this unlocking link is controlled by a control element located on the side of the seat pan framework and connected to the unlocking link 4 by a connecting rod 6. The connecting rod 6 is held onto the link 4 by an attaching part such as, for example, a clip 7 also of a known type. This clip determines the position of the rod 6 in relation to the unlocking link 4 while authorizing their relative pivoting. The connection between the rod and the control element 5 is ensured by a pin 8 attached to a link 9 of the said control element. The rod 6 passes through a diametral hole in the pin and the positioning of the rod in relation to the control link 9 is ensured by translation locking means, such as a locking washer 10, preventing the rod from sliding in the said pin. In direction only, blocking in the other direction not being required as the articulation mechanism includes elastic return means for the unlocking link 4 and the control element only needs to pull on the rod to control unlocking.
The relative positioning of the unlocking link 4 and the control link 9 is determined therefore by the effective length of the rod and, therefore, by the position of the washer 10 on the rod. This positioning must ensure that the control rod 9 bears on and cannot rotate in relation to the housing 11 of the control element 5 when the locking link is in its mechanism 1 locking position, this especially to avoid play in the control link and any noise which may result.
On account of the dispersions which can exist between various seats concerning the distance between the articulation mechanism and the control element 5, it is necessary, when installing such a device on a seat, to adjust the effective length of the rod and therefore to adjust the position of the washer on the rod. Also, during later use of the seat, there is a risk that the washer may slide on the rod under the tensile loads exerted on the rod by the unlocking link with the appearance of play between the pin and the washer. consequently, when the washer comes too far from the pin, the unlocking link will no longer control the articulation mechanism.
To avoid these problems, it would be possible to adjust and maintain the position of the rod in relation to the pin 8 by a nut screwed onto a thread made on the rod. Such a solution has the disadvantage of being more costly, increasing the device installation time and is also liable to misadjustment if the nut is not secured in rotation.
Whatever the case, these systems also have the disadvantage of requiring, during installation, the insertion of the rod into the pin along the axial direction of the rod which may complicate the installation due to the limited rotational travel of the links 4 and 9.
Similar problems may arise in all cases where a connection is required between a rod and an element controlling the movement of this rod with accurate relative positioning.